Heat shock protein and Cathepsin B genes play important roles in cadmium stress response in whitefly Bemisia tabaci

Cadmium, a highly toxic heavy metal pollutant, rapidly accumulates and persists in organisms including the globally distributed agricultural pest Bemisia tabaci. While previous studies established that cadmium exposure increases whitefly mortality and reduces abundance of the beneficial endosymbiont Rickettsia, the underlying mechanisms remain poorly characterized. This study reveals cadmium's effects on Bemisia tabaci: cadmium stress significantly stimulated oviposition in B. tabaci females (+47.97-57.09 %) but markedly reduced egg hatchability (-34.94 %, p < 0.01) and Rickettsia abundance (13.38 % of controls, p < 0.01), concurrently inducing pathological nuclear pyknosis in tissue cells. Transcriptome profiling identified 529 differentially expressed genes, with enrichment analyses revealing pronounced regulation of heat shock protein genes (BtHSP₁/BtHSP₂) and cysteine cathepsin genes (BtCTSB₁/BtCTSB₂). Targeted RNAi silencing demonstrated that BtHSP₁ knockdown significantly increased mortality in healthy adults (2.57-fold vs. dsEGFP controls, p < 0.01) and exacerbated cadmium-induced mortality and nuclear pyknosis. Conversely, BtCTSB₂ silencing conferred protection against cadmium toxicity, reducing mortality by 63.27 % (p < 0.01) and alleviating cellular damage. Notably, BtHSP₂ and BtCTSB₁ silencing specifically enhanced oviposition (+77 % and +67 % respectively, p < 0.05). These results establish BtHSP₁ as a cadmium-sensitivity factor and BtCTSB₂ as a cadmium-resistance determinant, revealing their antagonistic roles in stress response and suggesting novel RNAi-based strategies for whitefly control in cadmium-contaminated agroecosystems. ENVIRONMENTAL IMPLICATION: Heavy metal pollution is detrimental to the health of humans and ecosystems. Heavy metals can accumulate in insects through the food chain and food web, poisoning them and impacting pest control strategies in farmland. This study uncovers the biological and physiological impacts of exposure to the heavy metal cadmium on the broadly distributed agriculture pest Bemisia tabaci. By elucidating key molecular responses, this research paves the way for RNAi-based strategies to control whiteflies in contaminated agricultural environments, highlighting the interconnected challenges of pollution control and sustainable pest management.